The file system of a hard disk or optical disc may lose consistency by an unexpected event during recording, e.g. a power failure, since the file system update is usually done at the end of recording. An interruption especially during the recording of long streams, corresponding to large files, leads to a loss of already recorded streaming data, e.g. video recordings on optical discs like DVDs or Blu-Ray discs.
A proposal to solve the problem of power failure during recording, being disclosed in EP1102275, restores file management information that was destroyed or lost when recording a file. For this purpose, an initial indication of the beginning of a recording is entered in the file allocation table (FAT) of the file management system stored in the system area of a storage medium, and file management information is temporarily stored on a memory during the recording process. When the recording is finished, the file system in the system area of the storage medium is updated by copying the file management information from the memory to the storage medium. For detection of a discontinuous point in the stream, time stamps or program clock reference (PCR) values are detected and compared. However, this method is not adaptable to applications like DVD-VR (Video Recording), HD-DVD or Blu-Ray discs which use neither FATs nor PCRs or comparable time stamps. E.g. DVD-VR uses the Universal Disk Format (UDF) file system defined by the Optical Technology Storage Association (www.OSTA.org), which employs no separate system area on the storage medium, but contains a directory and file structure based on linked lists, i.e. distributed directory and file information.
Also journaling file systems like e.g. the NT File System (NTFS) are able to keep an unambiguous state of the disk. NTFS has features to improve reliability, e.g. transaction logs, to help recover from disk failures. Anyhow, NTFS like other file systems is not aware of the already recorded amount of data during stream recording. If a failure occurs, the whole data stream recording must be repeated. Journaling file systems require a lot of pick-up jumps on the disk, compared to e.g. UDF.